Induction-motor.



M. 0. BERTHOLD.

INDUCTION MOTOR. APPYLIOATIO'N FILED JUNE 5, 190a.

Patented July 25, 1911i 2 SHEETS-SHEET 1.

M. 0. BERTHOLD.

INDUCTION MOTOR. APPLICATION FILED JUNE 5, 1908.

998,868, Patented July 25,1911.

2 SHEBTSSHEET Z.

k fifrzesses in. Berf/zoia UNITED STATES PATENT OFFICE.-

MARTIN BERTHOLD, OF INDIANAPOLIS, INDIANA, ASSIGNOIR TO FAIRBANKS-MORSE ELECTRICAL MANUFACTURING COMPANY, OF INDIANAPOLIS, INDIANA, A COR- PORATION OF INDIANA.

INDUCTION-MOTOR.

Specification of Letters Patent.

Patented July 25, 1911.

' Application filed June 5, 1908. Serial No. 436,854.

is a specification, reference being had therein to the accompanying drawings.

The invention has particular reference to rotors for induction motors, and consists in an electrical appliance of this character having a maximum amount of ventilation and a more uniform radiation of heat.

The invention also consists in retaining means for the conducting bars, serving to prevent the latter becoming loose under the vibration and centrifugal motion, thereby maintaining the conductivity in the joints under all conditions in use, and it further consists in a novel form of joint between the bars and short-circuitiiig devices having the same or greater conducting area than the cross section of the bar, whereby overheat-' in and conse .uent im )airment is obviated.

I a u I 4 The lnventlon still further consists in the peculiar arrangement and combination of .the various arts of the rotor and in certain details of construction, as will be more fully hereinafter set forth.

In the dra.Wings,I+igure 1 is a side elevation of my improved'rotor; F 2 is a vertical central section therethrough: Fig. 3 is an end view; Fig. 4 is a cross section on line a7-m of Fig 2; and Figs. 5 and 6 are sectional views illustrating modifications of the end rings for the rotor.

In general, the rotor is of the well known squirrel-cage type, comprising a suitable core A, short-circuiting rings B of appropriate conducting material arranged at the core ends, and longitudinal conducting bars (I extending circumferentially about the core and contacting with the rings. In its improved form the rotor is provided with a considerably greater number of longitudinal bars than heretofore employed, and

these in turn are fashioned into thin flat conductors as illustrated, which When as sembled produce a better and more uniformly ventilated structure, producing a maximum dissipation of heat. The rotor bars described are connected to the short circuiting rings in the manner indicated in Fig. 2, each bar being notched adjacent'its opposite ends to embrace the rings and the joints soldered to produce an electrical connection between the parts.

It is well recognized in rotor construction that the greatest diiliculty is experienced in maintaining the conductivity in the joints between the rotor bars and short circuiting rings, even when the number of bars relatix'ely small and their cross section large, and this difficulty is obviously increased when the number of conductors is relatively large, as in the present construction of rotor, and their cross sectional area too small to permit of bolting in place. Furthermore, with the ordinary form of joint between a thin flat conductor as described and its contacting ring the conductivity of the joint would be less than that of the cross section of the bar, and the structure liable to overheating at the joint and consequent impairment. To obviate these difficulties I provide electrical connections between each bar and the complementary rings in addition to the ordinary joint. which connections with the bar contacts pro vide not less than the same, and in most instances several times greater, conductivity in the joint than in the bar itself, so that overheating of the joint is effectively prevented. The same means that form the electrical connection also preferably constitute the mechanical coupling which positively holds the bars in cont-act with the short-eireniting rings. and thus serves to maintain under all conditions of use the conductivity in the joints. The electrical connections referred to are formed by means of. end rings I) E arranged beyond the short-circniting rings. and spaced a slight distance therefrom. Each longitudinal condnetor extends beyond the main short-cin euiting rings. as shown, a slight distance, and its free end is squared, so that the bar end will contact with the outer ring. The rings in turn are preferably held in-place by means of bolts or screws F which extend outer members; the projecting portions of the longitudinal. conductors are clamped between the rings by the bolts or screws, and the latter are preferably made .of conducting material so as to form electrical connections between the rings which they connevi. Each of the outer rings described i the longitudinall conductors, as shown, thus holding the latter in place and preventing any possibility. of the bars working loose,

and at the same time the flangeswhich are *formed integral with the outer rings form a part of the electrical connections, increas ing the conductivity-of the joint.

The preferable construction of rotor comprises a hub' section II keyed to the lrotor end proper; in contradistinction to that por;

shaft I, and the core is of the laminated type, arranged upon the hub shownv and tightly clamped between the flanges J and K, which are heldtogether by suitable bolts L. -T he conducting bars are preferably arranged in longitudinal recesses M formed in the core, and the ends of the bars on their upper sides are notched, as at 0-, the notches formingan annular seat which receives the flange of the end retaining ring. \Y

In theniodification illustrated in Fig. 5 the outer rings P are positionedwithin annular seats formed by recesses a in the con ductor bar ends. The additional contact is thus provided, and the ring also serves as aretaining means, preventing the dislodgment' of the rotor bars.

In Fig. 6the outer ring isdesignated by thereference-letter R. In this instance, it encircles the end portions of the longitudinal bars, and the'connecting deiiices S for the rings extend intermediate of the bars in right angular relation thereto, instead-of relatively longitudinally as in the other instances. From this construction, it will be obvious that the-same functions are performed by the outer rings as in the other cases previously described.

In describing the conducting bars, the word end is used in the specification and claims as referring to the crosssecti'onal surface at the extremity of the bar, or the bar tion of the "bar adjacent its end.

What I claim as my inventioii is,

,1. A rotor, comprising 'a core,- short-circuiting rings adjacent the core ends," longitudinally-extending conducting :bars contacting with and projecting beyond the rings, conducting rings engaging the bar ends,fand connections of conducting materialbetween the rings.

2. A rotor, comprising a core, a" circum-' ferential series of longitudinal conducting bars thereon, short-circuiting rings'for the bars positioned within the series, in proxtar-1t .to its ends, conducting rings engaging 'ar ends'and forming retaining means for the bars, and connections of conducting material between the rings.

section as engaging the recesses in said bars and form ing. a-retaining means for the bars.

4. A rotor comprisin a core, a circumferential series of longitudinal conducting bars, engaging the core and projecting beyond the ends thereof, said bars being transversely recessed in proximity to their ends and having their ends also recessed, short circuiting rings positioned within the series of bars and en gaging the transverse recesses thereof, and continuous conducting rings of angular cross section abutting the bar ends, the laterally. projecting portions of said rings engaging the recesses in the ends of the bars and forming a retaining means for said bars.

5. A rotor, comprising a core, a circumferential series of longitudinal conducting bar extremities, and [continuous conducting rings of angular cross section fitted on the bar ends, said rings abutting the bar ends and overlying the portions of the bars adjacent the ends thereof. I

7. A rotor, 0on1 rising a core, a circumferential series of ongitudinally conducting bars thereon, short circuiting rings for the bars positioned within the series in proximity to its ends, conducting rings provided with portions abutting the bar ends and with portions overlying the tops of the bars adjacent the ends thereof, and means connecting said short circuiting rings and said conducting rings.

In testimony wuereof I aiiix my signature in presence of two witnesses .MARTIN O. BER-THOLD.

lVitnesses:

SAML. Lnn HADLEY, Ennnsr G. Cox. 

